diff --git a/internal/client/TLS.go b/internal/client/TLS.go
index a1b6cbb..f1c3aff 100644
--- a/internal/client/TLS.go
+++ b/internal/client/TLS.go
@@ -23,14 +23,6 @@ func makeServerName(serverName string) []byte {
 	return ret
 }
 
-func makeNullBytes(length int) []byte {
-	ret := make([]byte, length)
-	for i := 0; i < length; i++ {
-		ret[i] = 0x00
-	}
-	return ret
-}
-
 // addExtensionRecord, add type, length to extension data
 func addExtRec(typ []byte, data []byte) []byte {
 	length := make([]byte, 2)
diff --git a/internal/client/chrome.go b/internal/client/chrome.go
index eb266be..5d0c04b 100644
--- a/internal/client/chrome.go
+++ b/internal/client/chrome.go
@@ -71,7 +71,7 @@ func (c *Chrome) composeExtensions(serverName string, keyShare []byte) []byte {
 	// len(ext[16]) = 229 - len(ext[1])
 	// 2+2+len(padding) = 229 - len(ext[1])
 	// len(padding) = 225 - len(ext[1])
-	ext[16] = addExtRec([]byte{0x00, 0x15}, makeNullBytes(225-len(ext[1]))) // padding
+	ext[16] = addExtRec([]byte{0x00, 0x15}, make([]byte, 225-len(ext[1]))) // padding
 	var ret []byte
 	for _, e := range ext {
 		ret = append(ret, e...)
diff --git a/internal/client/firefox.go b/internal/client/firefox.go
index 380d3a1..17ad04c 100644
--- a/internal/client/firefox.go
+++ b/internal/client/firefox.go
@@ -42,7 +42,7 @@ func (f *Firefox) composeExtensions(serverName string, keyShare []byte) []byte {
 	ext[12] = addExtRec([]byte{0x00, 0x1c}, []byte{0x40, 0x01}) // record size limit
 	// len(ext[0]) + 237 + 4 + len(padding) = 399
 	// len(padding) = 158 - len(ext[0])
-	ext[13] = addExtRec([]byte{0x00, 0x15}, makeNullBytes(158-len(serverName))) // padding
+	ext[13] = addExtRec([]byte{0x00, 0x15}, make([]byte, 158-len(serverName))) // padding
 	var ret []byte
 	for _, e := range ext {
 		ret = append(ret, e...)